Automatic rhythm sound producing device adapted for use with keyboard musical instruments

ABSTRACT

An automatic rhythm sound producing device built in a keyboard musical instrument capable of playing ordinary tones of the melody, chord or bass, or combinations thereof upon selective depression of a plurality of keys arranged in the order of musical notes. The device includes a combination pulse generator which comprises a clock pulse generator followed by a frequency dividing counter chain to generate combination pulses, and having a resetting arrangement. The outputs from the combination pulse generator are supplied to a timing pulse encoder so as to cause outputs of the various stages of the counter chain to appear on the output lines of the encoder as a train of selected timing pulses which represent desired rhythm patterns. The outputs from the encoder are supplied to individual rhythm sound generators to produce rhythm sounds according to the selected rhythm patterns for an automatic rhythm performance. A trigger generator is provided to detect a depression of a key and upon detection to start the normally reset counter chain, thereby initiating the automatic rhythm performance.

United States Patent Ichikawa 1 Dec. 26, 1972 54 AUTOMATIC RHYTHM OU3,291,910 12/1966 Nicklas et a1 ..307/220 X I 1 PRODUCING DEVICE ADAPTEDFOR 3,490,327 1/1970 Volpe ..331/51 x 2,931,922 4/1960 Tubinis ..307/223U WITH KEYBOARD MUSICAL 3,546,355 12/1970 Maynard ..s4 1.03 INSTRUMENTS3,567,838 3 1971 Tennes ..s4 1.03 x 3,247,307 4/1966 Campbell ..84ll.24X [721 XII/"Sm lchlkwa Hamak'Fa, Japan 3,482,027 12/1969 Okamoto et a1..s4 1.03 [73] Assigneez Nippon Gakki Seizo Kabushiki 3,549,774 12/1970Hunger ..84/l.03 Kaisha, Hamamatou-shi, Shizuokaken Japan PrimaryExammer-Rwhard B. W11k1nson Assistant Examiner-U. Weldon [221 FlledlMarch 1971 Attarney-Flynn & Frishauf 21 A 1. N 121,387 I 1 pp 57ABSTRACT An automatic rhythm sound producing device built in [30]Foreign Application Priority Data a keyboard musical instrument capableof playing or- 2 dinary tones of the melody, chord or bass, or com-March 10, 1970 Japan "25/1508 binations thereof p Selective depressionof a p March 10,1970 Japan 5/ 911 y of y arranged in the Order ofmusical notes- The device includes a combination pulse generator [52]which comprises a clock pulse generator followed by a 0f 00 frequencydividing counter chain to generate com- [51] f i DIG bination pulses,and having a resetting arrangement. [58] d 0 can l 5 3 5 The outputsfrom the combination pulse generator are 30 2 supplied to a timing pulseencoder so as to cause outputs of the various stages of the counterchain to appear on the output lines of the encoder as a train of [56]Rderences d selected timing pulses which represent desired rhythm UMTEDA E TENTS patterns. The outputs from the encoder are supplied toindividual rhythm sound generators to produce 3,383,452 5/1968Parkketal. rhythm Sounds according to the selected rhythm Pat 2 l e mzlll IIIIIIIIIIIIIIIII x terns for an automatic rhythm performance. Atrigger 358589l 6/1971 Schwartz generator is provided to detect adepression of a key 3473633 H1969 jf' and upon detection to start thenormally reset counter 3:548:066 12 1970 Freeman... ..84/1.24X chain,thereby initiating the automatic rhythm P 3,358,068 12/1967 Campbell..84/l.03 X formance.

7 Claims, 6 Drawing Figures 3 6 l F 111111111 -1 32 34 311 312 3g?) 3In3S5 VRI A S TONE TONE COLORING g 1 KEYER g AMPLIFIER GENERATOR v IFILTER 1 I L j J COMBINATION TIMING PULSE RHYTHM SOUND PULSE GENERATORENCODER GENERATORS S I f t 39 40 3 8 41 VR2 TRIGGER GENERATOR 3?PATENTEDHECZG I972 3.707.594

SHEEI 5 0F 5 F l G. 5 "r2 I712 i n S S TONE CHORD CHORD GENERATORDETECTOR MEMORYk SW'TCHER BASS MEMORY SW|TCHER 7 RHYTHM PATTERNGENERATOR F l G 6 S 1 f f T CLOCK PULSE GENERATOR FF FFZ FF3 FF4 1AUTOMATIC RHYTHM SOUND PRODUCING DEVICE ADAPTED FOR USE WITH KEYBOARDMUSICAL INSTRUMENTS BACKGROUND or THE INVENTION ment, for example, anelectronic organ, there has recently been morefavorably accepted a typein which there is incorporated an automatic rhythm sound producingdevice having a rhythm section for playing the percussion sounds of theclaves, cymbals, tom tom, cowbell, or bass drum or the tones of themelody, chord or bass or combinations thereof in exact timing with arhythm pattern selected from various rhythm tempos or patterns such asthe march, rumba, tango, samba, waltz and bossa nova.

FIG. 1 is a schematic circuit diagram of a conventional keyboardelectronic musical instrument in which there is incorporated theaforementioned type of automatic rhythm sound producing device. The maindevice of the musical instrument consists of an organ section 16comprising keyboards 12 having a plurality of keys 11,, 11 11, arrangedin the order of musical notes; keyers 13 associated with the keys 11, ofthe keyboards 12 and provided with a plurality of keying switchesoperated upon selective depression of the corresponding keys; tonegenerators 14 designed to enable to generate tone signals having pitchespreset for the respective keys and, upon selective operation of thekeying switches, produce the corresponding tone signals therefrom; andtone coloring filters 15 so designed as to form musical sounds havingdesired tone colors from the tone signals, On the other hand, theautomatic rhythm sound producing device consists of a rhythm section 25comprising a combination pulse generator 22 formed of a clock pulsegenerator followed by a frequency dividing counter chain for selecting adesired rhythm pattern from among thevarious types of rhythm patternsand actuated by a normally open switch 21 manually closed at the startof a rhythm performance; a timing pulse encoder 23 consisting of aproper logic circuit including diodes in matrix arrangement so as toselectively form a train of timing pulses corresponding to adesiredrhythm pattern from combination pulses supplied from the generator 22;and rhythm sound generators 24 for generating rhythm sound signals beingtriggered by the timing pulses. The resultant output signals from thesections 16 and 25 are conducted'through separate volume controllers VR,and VR, respectively and one common amplifier A which may be providedseparately) to be reproduced from a loud-speaker S (which may beprovided separately).

However, where it is desired to play both the tones of the melody, chord'or bass or combinations thereof fromthe section 16 and the rhythmsoundsfrom the section 25, the conventional instrument having anautomatic rhythm sound producing device built therein in theaforementioned manner has the drawbacks that there is not only requireda troublesome process of operating the start switch 21 for rhythm soundperformance in addition to selective depression of a desired key on thekeyboards 12 for musical scale tone performance, but also there arepresented appreciable difficulties in exactly timing the initiation ofrhythm sound performance with that of musical tone performance.

Further, the prior art instrument generally so designed as to play asmany varieties of performance as possible by full working of both handsand feet of a player has a disadvantage that when additionally equippedwith the afore-said rhythm section 25, then the payer is obstructed inproducing such varieties of performance due to the required operation ofthe start switch 21.

It is, therefore, the object of the present invention to provide a noveltype of automatic rhythm sound producing device adapted for use with akeyboard electronic musical instrument enabling the automaticallysynchronous start of the rhythm sounds with the ordinary melodytones oraccompaniment sounds, thereby always exactly timing the performance ofrhythm sounds from the rhythm section with that of musical tones fromthe organ section and effecting ,performance in a far greater variety.

SUMMARYOF THE INVENTION According to an aspect of this invention, thereis provided an-automatic rhythm sound producing device incorporated in akeyboard electronic musical instrument for playing the ordinary tones ofthe melody, chord or bass or combinations thereof upon selectivedepression of a plurality of keys arranged in the order of musicalnotes, which device comprises a combination pulse generator formed of aclock pulse generator followed by a frequency dividing counter chain togenerate combination pulses and having a resetting arrangement. Theoutputs at various counter stages are supplied to a timing pulse encoderto produce a train of selected timing pulses representing desired rhythmpatterns, and outputs from the encoder are supplied to individual rhythmsound generators, to produce rhythm sounds according to the selectedrhythm patterns for an automatic rhythm performance. A trigger generatoris providied to detect a depression of thekey and upon detection tostart the normally reset counter chain thereby initiating the automaticrhythm performance.

Further, this invention provides an automatic rhythm sound producingdevice adapted for use with a keyboard electronic musical instrumentwherein there are provided normally open switches for each of severalkey stages, for example, upper, lower and pedal keyboards and those usedin common to all the key stages, and all key operation mechanisms arecoupled with the combination pulse generator through the switches,thereby enabling desired rhythm sounds to be played either at the startof performance or at any desired time during performance upon selectivedepression of the keys of each or all key stages.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic circuit diagramof a prior art automatic rhythm sound producing device used with akeyboard electronic musical instrument;

FIG. 2 is a schematic circuit diagram of a keyboard electronic musicalinstrument provided with an automatic rhythm sound producing deviceaccording to an embodiment of this invention;

, the trigger generator and combination pulse generator of-FIG. 2;

FIG. 4 is a schematic circuit arrangement of an automatic rhythm soundproducing device according to 'another embodiment of the .inventionadapted for use with a keyboard electronic musical instrument;

. FIG. 5 isa schematic circuit arrangement of an automatic rhythm soundproducing device according to still another embodiment of the inventionadapted for use with a keyboard electronic musical instrument; and

FIG. 6 is an another schematic circuit arrangement of the mainpart ofconnection between the keyboard and rhythm pattern generator accordingto the invention. DESCRIPTION or THE PREFERRED EMBODIMENTS FIG. '2 is aschematic circuit diagram of a keyboard electronicmusical instrumentprovided with an automatic rhythm'sound producing device according to anembodiment of this invention. The organ section 36 of the instrumentcomprises several keyboards 32, forexample, upper, lower and pedalkeyboardsrhaving a plu-' 4. ple,a diode D. The emitter of the transistorTR, is directly grounded, whereas those'of .the remaining I transistorsTR, to TR, are grounded through a normally open switch 54 closedby aplayer only when there are to be played rhythm sounds from the section37. On the other hand, the combination pulse generator 39 comprises aclock pulse generator 39a formed of an astable vibrator having, forexample, two transistors TR and TR and which generates a clock pulsetrainwhich is a multiple of the basic rhythm frequency of the device;and a binary counter chain 39b formed of a pluralityof flip-flopcircuits FF,, FF FF, and FF 4 of FIG. 3 (where there is shown indetailonly one ofthe' circuits, the others being indicated in blocks)cascadeconnected in turn to the clock pulse generator 39a,each of theflipflopcircuits including two transistorsTR and TR In this case,theemitters of the two transistorsTR and TR constituting the clock pulsegenerator 39a and the emitters of the corresponding ones included ineach group of the paired TR and TR of the cascade connected flip-flopcircuits constituting the binary counter chain 39b are directlygrounded,whereas'the emitters tone signals therefrom; and tone coloringfilters for properly adjusting the colors of tone signals generated soas to form the ordinary'musical tones of the melody, chord or bass orcombinations thereof. In addition to the above-mentioned organ section36, the instrument includes'a rhythm section 37 enabling rhythm soundssuch as'the desired percussion e.g. cymbals,'maracas,

' drums, etc. sounds and the ordinary tones of the chord or bass soundsor combinations thereof to be played in exact timing with varioustempos, for example, the march, tango, samba, bossa nova and waltz. Inthis c ase,'the present invention is so designed as to enable bothmusical tones from the organ section 36 'and rhythm sounds from therhythm section 37 to be played upon selective depression of the keys 31,to 31,, on the keyboards 32 using, as described above, output signalsfrom the filter 35 or keyer 33. Namely, the present invention includes atrigger generator 38 which receives outputs from the filter 35 or keyer33 to energize a combination pulse generator 39 as later described. FIG;3 isa concrete-circuit arrangement-of the generators 38 and 39. Thetriggergenerator-38 comprises an amplifier section 38a having threecascade connected transistors TR,, TR, and TR to amplify tone signaloutputs from the filter 35 or keyer 33; a wave shaper 38b consistingof aclipper 51 having two transistors TR, and TR, cascade connected to theamplifier section 38a and a differentiation circuit 52 having acapacitor C and a resistor R connected to the output terminal of theclipper 51; and a bistable multivibrator 38c having two transistors TR,and TR, so arranged that the base of either of them is supplied withrectified signals obtained by passing output differentiation signalsfrom the shaper 38b through a rectifier 53 using, for examresettingarrangement) the collector of one'transisto TR, of the bistablemultivibrator 38C. I

Where, in the afore'said circuit arrangement, there are not supplied theaforementioned output signals from the filter 35 or keyer 33 to theamplifier section 38a with the switch 54 closed,'tha t is, where thereis not depressed any of the keys 31, to 31,, on the keyboards 32, theother transistor TR, of the bistable mulitivibrator 38c becomesconductive, while the one transistor TR, remains nonconductive. Forthepurpose of the present invention, the bistable multivibrator 38c isso designed in advance as to reverse the above-mentioned condition onlywhen it is supplied with output signals from the filter 35 or keyer 33,that is, to cause the other transistor TR, to become inoperative and theone transistor TR, to be fired. I Where the aforesaid circuitarrangement is in a normal condition where there is not depressed any ofthe keys 31, to 31,, on the keyboards 32, the transistor TR, isconductive and the transistor TR thereof remains nonconductive.Accordingly, the flip-flop circuits FF, to FF, constituting each twohalves designed in the same way and the binary counter chain 39b remaindeenergized. Upon selective depression of any of the keys 31, to 31,,,however, the binary multivibrator 38c presents a reversed condition,that is, where the transistor TR, becomes nonconductive and thetransistor TR, is energized. As a result, the emitters of thetransistors constituting each set halves of the flipflop circuitsincluded in the binary counter chain 39b are grounded through thecollector of the short-circuited transistor TR, to render the flip-flopcircuits energized. Thus the condition of the flip-flop circuits FF, toFF, is reversed to cause combination pulses consisting of binary outputsobtained by successive downward frequency divisionof clock pulses fromthe generator 39a to bedrawn out of the output terminals 1-No. 1,l-No.i2, l-No. 3' and l-No. 4 on the set halves of the flip-flopcircuits FF, to FF,

Referring again to FIG. 2 a timing pulse encoder or rhythm patterngenerator 40 consists of a logic circuit halves of the flip-flopcircuits are supplied to the cor-,

responding input terminals in a preset combination by the player, thenthere is produced from the predetermined output terminals a train oftiming pulses or rhythm pattern pulses exactly timed with the rhythmtempos selected from among those representing, for example, the rumba,march, tango, samba, waltz and bossa nova. The train of timing pulsesthus selectively obtained from the encoder 40 is supplied to a pluralityof rhythm sound generators 41 so arranged as to selectively generate theaforesaid varieties of percussion sounds so as to selectivelyexcite thepredetermined one of the rhythm sound generators 41 preset by theplayer. Thus depression of any -of the keys on the keyboards 32 causesthe desired tones of the melody, chord or bass or combination thereoffrom the organ section 36 with the well-timed start of the rhythm soundsfrom the rhythm section 37.

The automatic rhythm sound producing device arranged as described aboveaccording to the present invention for usewith a keyboard electronicmusical instrument not only enables the performance of musical tonesfrom the section 36 to be exactly timed with that of rhythm sounds fromthe section 37, but also the player to be free from the necessity ofoperating the start switch for the rhythm section as has been the casewith the prior art device and consequently allowing him to carry outperformance in as many varieties as possible by fully working his handsand feet. v

It will be noted that the concrete circuit arrangement associated withthe combination pulse generator 39, timing pulse encoder 40 and rhythmsound generators 41 of FIG. '2 are shown in detail in FIG. 1 and thedescription thereof set forth in Automatic Rhythm Device invented byRichard H. Campbell, Jr., US. Pat. No. 3,358,068 (Ser. No. 378,365).

Referring to FIG. 3, a variable resistor VR included in the clock pulsegenerator 39a is'intended properly to regulate the repetitive period ofclock pulses produced thereby. If, in FIG. 3, there is provided a switch55 shown in dotted lines between the vacant contact 54s of the switch 54and the collector of the one transistor TR of the bistable multivibrator380 connected in common to the emitters of the transistors constitutingthe each set halves of the flip-flop circuits FF, to FF,, then it willbe possible to start and stop a rhythm performance manually by a playeras in the prior art device, by closing the switch 55 with the switch 54being turned on the contact 54s.

FIG. 4 is a schematic circuit diagram of an automatic rhythm soundproducing device according to another embodiment of this inventionadapted for use with a keyboard electronic musical instrument. Where theinstrument is provided with several keyboards arranged,

- for example, in three stages, that is, upper, lower and pedalkeyboards 61, 62 and 63 the key switches 61, to 61,, 62, to 62,, and 63,to 63,, fitted to the keyboards 61, 62 and 63 respectively are jointlyconnected at one end to be grounded and at the other end to the base ofthe other transistor TR of a bistable multivibrator 381a having thesamearrangement as that of FIG. 3 through separate rhythm start selectorswitches 64, 65 and 66 for the three respective keyboards 61, 62 and 63and a common rhythm start selector switch 67 to all of them. The sameparts of FIG. 4 as those of FIG, 3 are denoted by the same numerals anddescription thereof is omitted. The automatic rhythm sound producingdevice of FIG. 4 arranged as described above enables desired rhythmsounds not only to be automatically obtained as in the precedingembodiment but also to be started selectively in response to theselected keyboard during performance upon depression of those keyscorresponding to the selectively clo'sed ones of the selector switches64 to 67. For example, with the switch 66 along closed and the remainingswitches 64, 65 and 67 left open, when the first measure of a tone isplayed by selectively depressing the keys 61, to 61,, and62, to 62, onthe upper'and lower keyboards 61 and 62 with both hands of a player andthereafter at the start of the second measure there are selectivelydepressed the keys 63, to 63,, on the pedal keyboard 63 with the playersfeet, then it will be possible to start an automatic rhythm performanceat the beginning of the second measure, being triggered by the pedalperformance.

Although not shown in FIG. 2, that embodiment should preferably includein the organ section such selector switches 64 through 67 as shown inFIG. 4 before connecting to the trigger generator 38.

FIG. 5 is a schematic block circuit diagram of an automatic rhythm soundproducing device according to still another embodiment of this inventionadapted for use with a keyboard electronic musical instrument. Theembodiment of FIG. 5 enables the ordinary tones of the melody and thoseof the chord or those ofv the bass adapted for the chord or combinationsthereof to be played upon selective depression of several of the keys71, to 71, arranged on keyboards 72 in the order of musical notes inexact timing with a desired rhythm pattern selected from among aplurality of rhythm tempos or rhythm patterns. The tones of a desiredchord consisting of a combination of several tone signals of theprescribed pitches obtained from a tone generator 73 upon selectivedepression of several keys on the keyboard 72 are conducted to a chorddetector 74;

This chord detector 74 is formed of, for example, a matrix circuithaving a plurality of input terminals energized upon selectivedepression of the keys 71, to 71, and is so designed as to detect thekind of chord thus supplied as well as to draw out the base tonesadapted for the detected chord from the tone generator 73.

The tones of the chord and bass thus detected are temporarily memorizedin the corresponding chord memory 75 and bass memory 76. A rhythmpattern generator 77 has substantially the same arrangement as theaforementioned timing pulse encoder including the bistable multivibrator38c and produces a desired rhythm pattern preset by the player uponselective depression of the keys 71 to 71,. The rhythm pattern generator77 regulates the actuation of switches 78 and 79 cascade connected tothe chord and bass memories 75 and 76 respectively according to thegenerated timing of an output rhythm pattern from the generator 77. Theautomatic rhythm sound producing device of FIG. 5 having the aforesaidarrangement generates the tones bass adapted therefor or combinationsthereof exactly timed-with the rhythm pattern all at the same time.

FIG. 6 illustrates a concrete circuit arrangement of the other. sectionfor triggering the binary counter chainupon selective depression of thekeys without using a start switch for a rhythm performance as is thecase with the conventional device. According to the embodiment of FIG.6, the aforementioned bistable multivibrator 38c is substituted by, forexample,,a field effect transistor. TR to perform an'equivalent functionto that of the. multivibrator 38c. Either of the electrodes open keyswitches82 to. 82,, selectively'closed upon selective depression of thekeys..The other terminal of each of the switches-82 to 82,, is groundedthrough a resistor R and connected through a diode 83, the diode beingconnected in the forward direction forthe current from DC supply source81, and resistor R the diode 83 and the resistor R being connected inseries, to a non-grounded side of a grounded capacitor C,, which in turnis connected to thegate electrode of the transistor TR whose sourceelectrode is grounded and whose drain electrode is connected to a+ l3supply source through aload resistor RL. The non-grounded side of thecapacitorC, is coupled to ground through a normally open switch 84.According to the circuit of the aforementioned arrangement,'where one ofthe keys is selectively depressed with the switch 84 left open and thecorresponding one of the switches 82, to 82,, is closed, then a D.C.current'from the DC supply source81 is charged into the capacitor-Cthrough the forward biased diode 83. The charged voltage is supplied tothe gate electrode of the transistor TR to bring it from anon-conducting to a conducting state. As a result, the voltage of thedrain electrode of the transistor TR is reduced substantially to aground level, performing an essentially equivalent action to that of theaforementioned bistable multivibrator 380. Even after thedepressed keyis released to open the corresponding key switch, the charge in thecapacitor C is kept as it has been, being prevented from discharging bythe now backward biased diode 83 and infinitely large impedance of thegate electrode of the transistor TR and as a result the automatic rhythmperformance is kept on.

When the switch 84 is closed, the voltage supplied to the capacitor C,is rapidly discharged therethrough to stop the automatic rhythmperformance.

What I claim is: 1 v

1. automatic rhythm sound producing device adapted for use with akeyboard musical instrument which includes a first playing sectionhaving-a plurality; ofkeys arranged in the order of musical notes'forplaying tones of a melody and those of an accompania frequency dividingcounter chain including-a plurality of counter stages and coupled withthe clock pulse generator for counting down to submultiples of thefrequency of signals generated from said clock pulse generator andincluding a resetting means for maintaining said counter chain normallyinoperative; i r i a timing pulse encoder connected tothe stages'of saidcounter chain for producing a plurality of rhythm pattern signals eachbeing comprised of a preset different combination of output signals fromsaidclock generator; 1 a plurality of rhythm sound generators suppliedwith said respective rhythm pattern signals for producing a presetrhythm'sound corresponding to a rhythm pattern selected from the outputrhythm pattern signals of said encoder; and circuit means coupled tosaid first playing section to generate a trigger pulse upon detection ofthe depression of a key in the keyboard of said separate first playingsection, and connected to said counter chain through the said resettingmeans to initiate the operation ofsaid counter chain responsive to saiddetection of the depression of a key in said first playing section,thereby automatically initiating generation of rhythm sounds.

2. The automatic rhythm sound producing device according to claim'lwherein said circuit means for triggering said counter chain includes abistablemultivibrator having two active circuit elements, means couplinga predetermined tone signal produced upon selective depression of thekeys to the input terminal of one of said elements to bring it to anonconductive state and to bring the other element to a conductivestate, and means coupling the outputterminal of said other element witheach stage of said counter chain to enable said counter chain.

3. The automatic rhythm sound producing device'according to claim 1wherein saidcircuit means for trig- I gering said counter chaincomprises a DC power supply with one electrode thereof grounded; aplurality of key switches connected to the other electrode of said DCpower supply for generating signals upon selective depression of thecorresponding keys; a rectifier for rectifying said generated signals; acapacitor for receiving the rectified signal and being chargedresponsive thereto; and an active circuit element having at least threeelectrodes with a first electrode coupled to said capacitor forsupplying a signal corresponding to said charged signal, with a secondelectrode coupled to each stage of said counter chain to'enable saidcounter chain through said element only upon selective depression of thekeys with a third electrode coupled to the said DC power supply. I

4. The automatic rhythm sound producing device ac-' cording to claim 1including a plurality of manual switches and wherein said keys arearranged on several keyboards, the ends on one side of the keys on eachkeyboard being jointly grounded, and the ends on the other side of thekeys on all the keyboards being jointly coupled 'with said circuit meansfor triggering said binary counter chain through corresponding manualswitches.

comprises an astable multivibrator.

7. The automatic rhythm sound producing device according to claim 1wherein said counter chain comprises a plurality of flip-flop circuitsconnected in cascade, the first stage of which is coupled with saidclock pulse generator.

1. An automatic rhythm sound producing device adapted for use with akeyboard musical instrument which includes a first playing sectionhaving-a plurality of keys arranged in the order of musical notes forplaying tones of a melody and those of an accompaniment upon selectivedepression of said keys, said first playing section being separate fromsaid automatic rhythm sound producing device, said automatic rhythmsound producing device comprising: a clock pulse generator forgenerating a repetitive frequency signal corresponding to a multiple ofthe basic rhythm frequency; a frequency dividing counter chain includinga plurality of counter stages and coupled with the clock pulse generatorfor counting down to submultiples of the frequency of signals generatedfrom said clock pulse generator and including a resetting means formaintaining said counter chain normally inoperative; a timing pulseencoder connected to the stages of said counter chain for producing aplurality of rhythm pattern signals each being comprised of a presetdifferent combination of output signals from said clock generator; aplurality of rhythm sound generators supplied with said respectiverhythm pattern signals for producing a preset rhythm sound correspondingto a rhythm pattern selected from the output rhythm pattern signals ofsaid encoder; and circuit means coupled to said first playing section togenerate a trigger pulse upon detection of the depression of a key inthe keyboard of said separate first playing section, and connected tosaid counter chain through the said resetting means to initiate theoperation of said counter chain responsive to said detection of thedepression of a key in said first playing section, thereby automaticallyinitiating generation of rhythm sounds.
 2. The automatic rhythm soundproducing device according to claim 1 wherein said circuit means fortriggering said counter chain includes a bistable multivibrator havingtwo active circuit elements, means coupling a predetermined tone signalproducEd upon selective depression of the keys to the input terminal ofone of said elements to bring it to a nonconductive state and to bringthe other element to a conductive state, and means coupling the outputterminal of said other element with each stage of said counter chain toenable said counter chain.
 3. The automatic rhythm sound producingdevice according to claim 1 wherein said circuit means for triggeringsaid counter chain comprises a DC power supply with one electrodethereof grounded; a plurality of key switches connected to the otherelectrode of said DC power supply for generating signals upon selectivedepression of the corresponding keys; a rectifier for rectifying saidgenerated signals; a capacitor for receiving the rectified signal andbeing charged responsive thereto; and an active circuit element havingat least three electrodes with a first electrode coupled to saidcapacitor for supplying a signal corresponding to said charged signal,with a second electrode coupled to each stage of said counter chain toenable said counter chain through said element only upon selectivedepression of the keys with a third electrode coupled to the said DCpower supply.
 4. The automatic rhythm sound producing device accordingto claim 1 including a plurality of manual switches and wherein saidkeys are arranged on several keyboards, the ends on one side of the keyson each keyboard being jointly grounded, and the ends on the other sideof the keys on all the keyboards being jointly coupled with said circuitmeans for triggering said binary counter chain through correspondingmanual switches.
 5. The automatic rhythm sound producing deviceaccording to claim 1 wherein said circuit means to generate a triggerpulse further includes selector switches for selectively detectingdepressions of keys in different keyboards.
 6. The automatic rhythmsound producing device according to claim 1 wherein said clock pulsegenerator comprises an astable multivibrator.
 7. The automatic rhythmsound producing device according to claim 1 wherein said counter chaincomprises a plurality of flip-flop circuits connected in cascade, thefirst stage of which is coupled with said clock pulse generator.